Cfrgtkky

I'm working in a project that I need read lines in a .txt file and push this lines into a List.

In my first prototype, in WPF, I used this very simple code to do this:

private static List<string> fileLines = File.ReadAllLines("WordList.txt").ToList();

However, now I am working at a Windows Phone 8.1 version and I can't do that in this way.

For now, my research come this code but no successfully:

public static List<string> fileLines = LoadingLines();



public static async Task<List<string>> LoadingLines()

{

    StorageFolder storageFolder = Windows.Storage.ApplicationData.Current.LocalFolder;

    StorageFile sampleFile = await storageFolder.GetFileAsync("WordList.txt");

    IList<string> text = await Windows.Storage.FileIO.ReadLinesAsync(sampleFile);



    return text;

}

Some problem that I have with this code is that I don't know if this returns a List where each line of the file is one element and if I try assign a Task> type to a List I have this error: Error 2 Cannot implicitly convert type 'System.Threading.Tasks.Task>' to 'System.Collections.Generic.List'

Maybe this code are totally wrong to what I need. Again, what I need is just read a .txt file in my packaged app and turn each line in an element of fileLines List. Obviously, after, I need access this List out of the method.

According to the documentation a call to ReadLinesAsync will return IAsyncOperation<IVector>, i.e. when you await it, this will return an IVector<string>. For this type, documentation states:

Represents a random-access collection of elements. .NET: This
interface appears to .NET code as System.Collections.Generic.IList<T>
due to .NET language projection. In any case where a Windows Runtime
type has implemented IVector, .NET code can use the APIs of
IList<T> instead.

So this line in your code should work fine

IList<string> text = await Windows.Storage.FileIO.ReadLinesAsync(sampleFile);

The problem is that text is of the type IList<string>, but the return type for your method is List<string>. You cannot assign an IList<string> instance to the return value of type List<string>.

To fix this, you can use one of the following two options:

1. 
   

   Change the signature of your method to

   
   
   

   public static async Task<IList<string>> LoadingLines()

   
   


2. 
   

   Convert your methods result to a List<string> when you return it:

   
   
   

   return text.ToList();

   
   

When you use the result returned from your method, you also must do so with the await keyword, so this line:

public static List<string> fileLines = LoadingLines();

Will not work correctly, because LoadingLines returns a Task<List<string>>. You cannot asynchronously load into a static member variable. If you want this to work (making minimal changes to your code)¹ what you can do is the following:

Remove this line:

public static List<string> fileLines = LoadingLines();

And replace it with:

private readonly static Task<List<string>> loadLinesTask = LoadingLines();



public static async Task<List<string>> GetLinesAsync()

{

    return await _loadLinesTask.ConfigureAwait(false);

}

You can then call GetLinesAsync() in other "async" methods. If you need to call this in methods that are not marked as async, you cannot use await and (using MyClass for the class with these methods) you will have to do this to get the list of lines:

var lines = MyClass.GetLinesAsync().Result;

¹ There are better ways to do this, but to discuss that that would go beyond the scope of this question.

1. Add the text file to your project. Right-click it, choose Properties and set the action property to "embedded resource".



2. 
   

   Access it as follows. The resource name is fully qualified name, meaning the namespace is included. (Ex. - "MyCompany.Project.Resouces.fileName.txt").

   
   
   

       var list = new List<string>();
   
       var assembly = Assembly.GetExecutingAssembly();
   
       var resourceName = "XYZ.ABC.Resources.MyTextFile.txt";
   
   
   
       using (Stream stream = assembly.GetManifestResourceStream(resourceName))
   
       using (StreamReader reader = new StreamReader(stream))
   
       {
   
           while (!reader.EndOfStream)
   
           {
   
               list.Add(reader.ReadLine());
   
           }
   
       }
   
       return list;